Combustion turbine



' April 13., 1926.

L. DUFOUR COMBUSTION TURBINE Filed May 24, 1922 3 "Sheec s-Sheet 2 April13 L. DUFOUR COMBUSTION TURBINE.

Filed May 2 4, 1922 3 Sheets-Sheet 5 combustion and for operating theturbine s-ta Apr. 13,1926.

' UNITED STATES- JZEON nuro'on, or emmv'a, swrrznnna'nn:

eomaus'rxon TURBINE.

Application filed Kay 24, 1922; Serial no.,.5oa,2o0; '1

To all whom it may concern:

Be it known that I, Lr'zon DUFoUR, a cltlzen of Switzerland, residing atGeneva,

Canton of Geneva, in the Confederationof Switzerland, have-inventedcertain new and useful Improvements in Combustion Turbines, of which thefollowing is a specificatiom Under the'general term combustion turbinethere is herein to be understood any machine which generates motiveforce in which the expansion of gases produced by the combustion of anyfuel such as gas, oil, tar, petroleum, petrol, coal and explosives,etc., is utilized by a turbine. It is known that combustion turbinescalled also gas turbines may be divided into two 'main classes, i. e.,turbines at'constant pressure and explosion turbines. This inventionapplies to both of theseclasses of combustion turbines.

The invention herein claimed relates to an apparatus in which thecooling of the wheels and of the blades of the wheels of acombustionturbine allows'a turbine to be constructed which possesses excellentconditions of efficiency and an arrangement for. carrying out suchprocess in a combustion turbine.

. The apparatus consists, in aj-combustion' turbine, in which the wheelsand especially their blades are cooled by passing cold air and ifdesired'thc cold gases necessary for into such wheels and blades, andalso if desired the burnt gases after they have performed their work inthe turbine and after they have been suitably cooled, while utilizingthe passage of the air and it may be gases in the wheels of the turbineat the sametimeto increase the pressure of such air and gases. Theapparatus also consists of a. turbine having a plurality of pressurestages, and one or more speed stages per pressure stage.

the turbine having'a plurality of wheels in which wheels and theirblades are so constructed as to serve both as turbine wheels andcompressorfwheels, and in which the wheels and their blades successivelyreceive burning active gases coming from'the combustion or explosionchamber or chambers,

gases whose speed and it may be-pressure 1s utilized by the wheels andthe cold air or gases compressed by such wheels. In'such turbines theblades of the same wheel are therefore successively employed totransform the pressure and speedor speed oInly of the active hotgasesinto rotary movement of the wheel, then to transform the rotarymovement of the wheel into speed and into pressure of the air or coldgases to be compressed. The heat communicated to the blades and to thewheel by the hotactive gases will be transmitted as produced by thewheel and the blades to the air'or to the cold gases so that-the wheeland the blades will be maintained at a temperature intermediate betweenthe temperature of the hot active gases and that of the air' or coldgases. 1

. Finally such arrangementcomprises sev-' e 'al parts or machineelements which will herein be successively described and whoseapplication to the new arrangement for a new object alto constitutesnovelty. p

The invention is illustrated by way-of example in which' Fig. 1 is adiagrammatic longitudinalsection of a combustiomturbine for carrying outthe process.

Fig. 2 is a transversb section taken on the line 22 of Fig. 1.

the accompanying drawings of" Figs. 3 and 4 show two arrangements of awheel for such turbine.

Figs. 5, 6, 7, 8-, 9, :10 and 11 show details of the-constructiono-f theblades of such Wheel and the method of securing them.

Finally Figs. 12-, 13' and 14 show three views of a Wheel provided withdifferent.

arrangements of blades.

The turbine illustrated by way of example in Figs. 1 and 2 is acombustion turbine burning liquid fuel, crude oil-for example, of theaxial type having five pressure stages, each pressure stage having onespeed stage only, three-of such stages working above atl mosphericpressureand the other two stages workingb elow atmospheric prezsure.The" turbine is divided into two sections of which the upper section asillustratedcomprises nearly three quarters of the circumference 'wherethe wheels work as rotary compressor wheels, and the lower section wherethe wheels work as turbine wheels properly so ca led.

In Fig. 1, a {is the turbine shaft, 6 b b 11 and 'Zr" are the fiveturbine Wheels keyed on shaft a. Each wheel consists of the portion 1)which comprises the hub keyed upon the shaft and flange -0 connected toortion b by ribs d forming portions ofthe blades. A circular'channel ,e,e is thus hill formed in each wheel between portions 7) and a'. Theblades f are fixed at the circumference of each wheel between portion 6and flange c. The blades are, outwardly to the wheel, of the generalshape of theprovided with blades fixed at their external radial portion.Blades f of the wheel pass with very little play into the internalradial portion of these channels. The diffusing channels communicatewith other channels b 7& b which connect channels g g and g with theinlet of the wheel following, and channelsg and g with the channels kand 12. leading to the outlet pipe for the gases or air. 2' is the inlettube for the burnt gases into the compressor and i the outlet tube forthe same burnt gases into the atmosphere. 2' is the inlet tube fortheair required for combustion and i theout let tubefor such air after itspassage into the compressor section.

In the lower portion of Fig; 1 in which the turbine acts as a turbineproperly so called, k k are channels leading gases pass ing out of theblades of one wheel to the guide blades of the following stage, m m arethe guide blades of each stage. the inlet tube for hot gases passinginto the turbine and passing out of the combustion or. explosionchamber, which isnot shown in the drawing. 0 is an outlet tube for saidgases passing out of the turbine after hav ing traversed the blades ofthe five wheels. 37 p are diaphragms separating the different pressurestages of the turbine from each other. 12 p are portions of saiddiaphragmswhich being situated 'very near to the inlet into channels 6of wheels I), serve to close the inlet to such channels when they passinto the section of the turbine properly so called. Behind each closingportion 12 is a channel u which allows the internal radial portion 9 ofthe channel or channels immediately preceding the turbine section tocommunicate with the internal radial portion of the channel or channelsimmediately following the turbine section. I I

Lastly s s is the outer wall creasing of the mach-inc.

Fig. 2 is a transverse section of the 'same turbine taken on the line 22of Fig. 1, said line. deviating from the straight according as thesection relates to the compressor portion or to the turbine properly socalled. In Fig. 2, a is the turbine shaft, h 72. chaneeds-2s nels whichleads air into the inner part of the compressor, and g the circular sace forming a continuation of: the prece ing diffuser and which allowssuch diffuser to communicate with channels 72.. i is the inlet tube forair into the compressor section. In the lower or turbine section 12 isthe diaphragm separating one pressure stage from the other pressurestage of the turbme. p is the portion of such diaphragm which closes theinlet of the channels of the wheel. k is the channel leading the gasespassing out of the blades of the preceding wheel to the directing bladesm. .r r are walls sepa rating the turbine section from the c0mpressorsection, r is an enlargement of wall 1' placed at the spot where thewheel passes from the compressor section to the turbine section andserving as the wall p to close the inlet of the channels of the wheel,such channels being marked 0 in Fig. 1. As seen in the figure suchclosing surface 9 p? is set at an angle with respect to tlie turbinesection and behind said portion 1' p is channel it shown dotted, butwhich can well be seen in Fig. 1; this channel allows the internalradial portion .of channels it preceding the turbine section tocommunicate with theend portion u. of channel a as shown in Fig. 2. s sis the outer wall or casing of the machine.

In Fig. 3 which shows one method of constructing a wheel I) is the Wheelhub forged in a single piece with the main disk 7).

cl (1 are ribs forged together with the disk and hub or formed bycutting away metal. Ribs cl are sharpened at d and at (P so that whenonce the wheel is mounted such ribs form blade elements. ondary disk ofwhich the enlarged portion a is in mounting fixed upon the corresponding rounded portion of ribs d. In Fig. 3 flange 0 is shown separate frommain disk I), and therefore before being mounted upon the disk.The'lesser diameter 25 of enlarged portion 0 is a little smaller thandiameter 25 above the commencement offthe ribs so that the flange 0should be mounted while hot when the temperature of the flange issufficiently high for diameter t ,to be a little larger than diameter 2,of the ribs. After cooling flange 0 is then firmly applied on ribs (1and flange 0 will be in some measure in one with main disk I). The diskand flange maintained at the required distance by ribs d will formbetween them a circular channel having walls converging towards theouter circumference provided the fian e.

seen in section is inclined. w o and o 2-0 are circular dovetail groovesformed on the internal facesof disk 7) and of flange c, said groovesserving to fix the blades.

In Fig. 4-. which shows another method of making the wheel the sameletters designate the same parts as in Fig. 3. In this other the diskmay also be combined together inand flange c.

arrangement enlarged portion of the flange is provided at m with aninternal screw thread and screws on to'ribs d which are at y providedwith an external screw thread. These two ways of mounting the flangeupon this sense that the flange may be screwed while hot upon the ribson the disk.

Fig. 5 is a front elevation of one of the blades fixed on the wheelbetween the main disk and the flange. f shows such blade which is formedof a sheet of metal suitably curved or forged to-the shape of a gutterjust as in a normal steam turbine blade. The blade however in this caseremains open at the internal radial end as also at the external radialend because it must serve both as turbine blade and as compressor blade.Lugs z z formed in one with the blade serve to secure it by engaginggrooves to 02 in disk .6 Such lugs may be dovetail as are the groovesindicated in the figure V 7 but this'is not a necessity. The figureshows responding dovetails.

two lugs and two grooves, one on eachside,

; but the number of lugs on each blade and their corresponding grooves.may be greater.

Fig. 6 is a profile view of the same blade, taken on the line 6 6 ofFig. 5.

Fig. 7 is a plan of the same blade and neighbouring blades takenon theline 7-7 of Fig. 5. In Fig. 7 a 2 are distance plates also seen'insection which are interposed between each blade and which are maintainedin grooves 'w 'w It is'mainly to fix these plates that. grooves w *w aremade dovetail:

and of course plates 2 are provided with cor- The plates are insertedinto the grooveby means of a notch indicated by dotted lines 9 in Fig,5, such notch being then filled up in any suitable manner. If the bladesin place of being radial as indicated in Fig. 5 are inclined withrespect to the radius of the wheel as shown in Figs. 13 'and14 thedistance plateswhich are inclined also may'in certain cases be'mserted1nto the groove in a very slmple manner; to insert them 1t 1s onlynecessary to incline them still more and then tostraighten them. Thelast plate of a tier is inserted after it has been curved sulficientlyto allow it to enterthe groove, it is then flattened. when .position.These plates maintain" the distance between the blades and cooperate inmaintaining the blades rigidly fixed.

Fig. 8 shows in front elevation, side elevation and plan 'twoqdifierenttypes of such plates. The left. hand plate is intended to separateradial blades such as those indi- 'cated in Fig. 12 and that on theright hand to separate inclined blades such as those in dicated in Figs.13 and 14.

Fig. 9 shows a blade similar to that shown in Fig. 5; in Fig. 9 howeverthe inclination of flange c seen in section continues as far as'theouter circumference of said flange so that the circular channel formedbetween flange c and main disk 6 is converging up to its end and so thatthe portion of the blade engaging such channel is trapezoidal as isclearly shown in Fig. 9. In Fig.5 the inclination of flange a ceases atthe base of blade f so that the walls of the channel between the flangeand the main disk become parallel near to the blade andso the portionof'the blade engaging in such channel is rectangular. In Fig. 1 thedifi'errntgvheelsare constructed according to both these methods.

Fig. 10 shows one ofthe long blades, 7':

with its two sets of lugs 2 2 and a 2 which are lodged in grooves w 'wand v '0 on the wheel. Each wheel comprises a certain number of shortblades and acertain number of long blades which may of course beprovided .with more than twopairs of lugs. A same from the blade, arerelatively very large measuring more than 40.

Fig. 12 shows a wheel with its blades in position seen in frontelevation. I11- this arrangement the blades are mounted radially andthere is always one long blade f for two short blades f. The circulargrooves 'w 4) which serve to maintain the blades in position areindicated by dotted lines.

Fig. 13 shows another arrangement of wheel in which the blades are nolonger mounted radially but are inclined rearwardly with respect to thedirection of. rotation of the wheel, and such inclination can easily beobtained by interposing between the blades in the grooves 'w 0 distanceplates having an inclined shape such as indicated on the right hand sideof Fig. 8. In this figure the wheel shown always has one long blade ffor every three short blades 7.

--F1nally Fig. 14 shows 'a third arrangement of wheel also havinginclined blades I but having for each long blade f four short blades fand one medium size blade f intermediate between and interposedsymmetrically between the short blades.

In this arrangement there is formed in the disk and in the flange athird pair of circular grooves 'w intermediate in size between grooves wand a); such grooves are particularly useful-for fixing the base ofmedium size blades f while they also support themiddle "portion of longblades f. The numberof types of blades of diiferent lengths may ofcourse be increased and they of Fig. 1.

may be arranged in no matter what order with a view to obtaining acompressor wheel of advantageous shape.

The working of the turbine shown diagrammatically and by way ofillustration in Figs. 1 and 2 can easily be understood; the airnecessary for combustion is sucked from the atmosphere through tube iand is compressed to the required pressure by the three wheels 6 b 6shown on the left hand side These wheels at the u per section of themachine behave exacty as the wheels of an ordinary rotary compressor.Air is first compressed inside each wheel by reason of the differencebetween the relative speeds of inlet and outlet and by centrifugalforce. The absolute outlet speed of air from the wheel is thentransformed into the blades of first wheel 6 in the lower sec-- tion ofthe machine which is the turbine section. The said first wheel from theturbine point of view is at the same time the last-wheel from thecompressor point of view. In passing out from the blades f of this wheelthe gases are directed by channel is into'guide blades m of the secondstage ofthe turbine and so on until the last stage and to last wheel 6In each series of guide blades the gases expand to a lower pressure andtherefore increase in speed which is then utilized by the correspondingwheel. In passing out of last wheel I) the gases have fallen to apressure lower than atmospheric pressure and they must be compressed inorder that they can escape into the at-' mosphere.-

At the moment whentthe blades ot a wheel 7 11 r is the inletinto-channels e of thev wheels and p T have for their object the e oft ewheels when the closing of suchinlet channels and thus "pre- .ventin airor'gases enterin into channels lades of such wheels are passing th'rou hthe turbine sec tion. Itis even'preferab e that the closing of thechannels'e should commence a mofrom the compressor section-into theturbine section in order that the air or the gases in the channels e atthe moment of closing still have time topass through the wheel as far asthe blades and.can still escape into the compressor section. In the samemanner it is preferable that closing of the inlet of channels 0 shouldcease before the blades have left the turbine section so that the air orthe gases may have time again to enter the wheel and to traverse itradially and to pass radially between the blades when these reenter thecompressor section. This is the [reason why closing portions 17 r inFig. 2 isset at an angle in advance of the direction of rotation of thiswheel with respect to the turbine section. In rear of the closingsurface a channel u places the internal radial portion of the channel itimmediately preceding the turbine section into communication with theinternal radial portion of the channel It immediately following suchturbine section so that continuous circulation of the.air or gases inthe compressor may not be interrupted e cept for the interruptionnecessary in the interior of the wheel as has above been explained.

The method of constructing the wheels and blades and the methodof fixingthe blades in the wheels will easily be under-' stood from thedescription of Figs. 3 to 11. In order to improve the working of thecompressorthe blades may be inclined rearwar'ds with respect to thedirection of movement ofthe wheel as has'been indicated in Figs. 13 and14. In this case the guide blades of the turbine may be given aninclination suitable to this inclination of the blades of the motivewheels. In each wheel blades of different. lengths may be alternated asis indicated in Fig. 12 to 14, in brief,-inside such wheels the bladesmay have the shape and be arranged as is most suitable from thecompressor point of view. The advantages of the process and the methodof carrying it out are evident by mere inspection of Figs. (1 and 2. Thecold gases or air passing into the compressor commence at once to coolthe blades which in the turbine section are in contact with f the'burning gases. The blades and the wheels'will thus at each stage of,the machine have a temperature intermediate between that of the burninggases and that of the cold air. or gases. Knowing the value of thecoefiicient of transference 'of heat between the g'asesor the air andthe blades for ent temperatures of the blades, the necessary speeds andcross sections may easily be found for the burning gases on the one handand for the cold gases or air on the other hand in order so to arrangethat the 0 ment before the corresponding blades pass bladesfdo notexceed a limited predetermined iao temperature. It ma be noted thatcooling is facilitated by the diet that the cold gases or air passradially between blades which have a relatively large radial heightwhile the burning gases traverse blades axially and a portion only oftheir radial height. The heat transmitted by the burning gases to theblades may partially be distributed over their whole radial height andwill thus more easily be dissipated by the cold gases and air. Forexample, in the first wheel of the, turbine the gases may be allowed toenterat atemperature of 900 or 1000 C. or more and the arrangementhowever be such that the blades do not exceed a maximum temperature of400 C.

From then on turbines having a pluralit of pressure stages may as shownbythe above described example, be employed as combustion turbines, forexample, turbines having to pressure stages or more, that is to say theturbines will possess efficiencies much greater than turbines having asingle pressure stage as has heretofore been proposed for combustionturbines.

It will be of advantage in each wheel that the pressure in thecompressor section should approximately be the same as the pressure inthe turbine section as the passage of aim or gases from one section tothe other, where the wheel passes from one to the other, would thus beavoided and so loss of air or gases. It is known however in rotarycompressors that when the tangential speed of the wheels does not exceed150 to 200 metres per second that the increase of pressure obtainedfromeach stage of wheel and diffuser is relatively small and is less thanthefall of pressurewhichcan be utilized in a correponding combustionturbine stage with the same tangential speed of the wheel.

A method of obviating the difiiculty of obtaining substantially the samepressure in a compressor section stage as in the corresponding stage ofthe turbine section will be to lessen that portion of the speed of theburning gases utilized by each turbine wheel in the turbine section byincreasing above the usual limits the angle of inclination of the guideblades upon the plane of the wheel. In normal steam turbines this anglevaries, between and An angle of at least may here be taken. The inletangle of the wheel blades will then have a'value of at least 40, a valuemuch'greater than the usual value. The proportion of the speed of thegases then utilized by the wheel and transformed by it into work will beless great than if the angles were normally small while the absolutespeed of outlet of the gases from the blades will be greater; suchabsolute outlet speed is moreover utilized to a large extent by thecrown of guide blades at the stage following. This means that the fallof pressure utilized by one stage of the turbine section will be smallerthan in a turbine having normal angles for the guide blades and theblades of the wheel and thus it will be easier-to make this small fallof pressure correspond to the increase in the pressure of the air or ofthe gases in the corresponding stage of the compressor secthe blade'willbe less curved the blade will be better suited to act as compressorblade for it is to be noted that in the compressor section it is theconvex surface or the back of the blades which is-the surface directlyacting upon the air or gases to be compressed.

The apparatus herein shown and described is illustrative of one mannerin which my invention may be carried out, and it is to be understoodthat the same may be varied within the scope of the claims withoutdeparting from the nature and spirit of the invention. 0 a

Having now particularly described and ascertained the nature of myinvention and in what manner the same is to be performed, I declare thatWhat I claim is 1. In an apparatus of the class described,

a casing, a plurality of rotors each having a mo passage therethrough, aplurality of blades carriedby the said rotors, means for admitting airinto the casing and to the said passages in the rotors during a part ofeach revolution thereof, for utilizing said blades as compressor blades,means for closing the entrance to the passage in each rotor during theremainder of each revolution thereof, means for'directing combustiongases to the said bladesduring the said remainder of each revolutionthereof, and thereby utilizing the said blades as turbine blades duringthis portion of the revolution, and inlet and outlet connections for thesaid combustion gases.

2. In an apparatus of theclass described, a casing, a pluralityof rotorsmounted in the casing, and each having a passage there through,arplurality of blades mounted in, and extending from the said rotors,means for admitting air into the casing and to the said passages in therotors during part of.

said blades as turbine blades ,'-and inlet and outlet connections forthe said combustion gases.

3. In an apparatus of the class described, a casing, a plurality ofrotors mounted in the casing, webs in the rotors providing ineachthereof a plurality of passages, a plu'- tion gases.

ing the said blades as turbine blades, and

inlet and outlet connections forthe combus- 4. In an apparatus of theclass described, a casing, a plurality of wheels revolubly mountedtherein, eachwheel comprising a primary disk, and a secondary diskspaced therefrom and secured thereto to provide a'pas'sage'therethrough, a plurality of blades mounted in each wheel,.meansfor admitting air into the casing and to the entrance to thepassages in the wheels during a part of each revolution thereof, forutilizing the said blades as compressor blades, means for closing theentrance to the said passages in the said wheels. during the remainderof each revolution thereof, means for directing combustion gases to thesaid blades during the said remainder of each revolution of thesaidwheels, for then utilizing the said blades as turbine blades, and inletand outlet connections for the combustion gases.

5. In an apparatus of the class described, a casing, a plurality ofwheels revolubly mounted therein, each Wheel comprising a primary disk,a secondary disk spaced therefrom and secured thereto, and webs betweenthe said disks providing passages therethrough, a plurality of bladessecured in 4 each of the said'wheels between the disks m'ainder of eachrevolution thereof, to then ut lize thesaid blades as turbine blades,and;

.t-here'of; means for admittingair through the casing and to thepassages in each wheel during a part of each revolution thereof, forthen utilizing the said blades as compressor blades, means for closingthe. entrance to the said passages through thesaidjwheels during theremainder of each revolution thereof, means for dlrectlng combustiongases to the said blades during the said-re,

inlet and outldt connections for the said combustion gases. 6. Inan'apparatus of the class described, a casing, a plurality of wheelsrevolubly mounted therein, each wheel comprising a primary disk, asecondary disk spaced therefrom and secured thereto, and webs providingpassages extending therethrough, a plurality of blades mounted betweenthe disks of each wheel, and extending therebeyond, means for admittingair through the casing and to the passages through the said wheelsduring a part of each revolution thereof, to then utilize the saidblades as compressor blades, partition walls in the casing closing theentrance to the said passages in the wheels during. the remainder ofeach revolution thereof, means for directing combustion gases to thesaid'blades during the said remainder of each revolution of the saidwheels, for then utilizing the said blades as turbineblades, and inletand outlet connections for the said combustion gases.

7. In an apparatus of the class described, a. casing, a plurality ofspaced wheels revolubly mounted therein, each wheel comprising.a primarydisk, a'secondary disk spaced therefrom and secured thereto, and websbetween the saiddisks forming a plurality of passages between'the same,the entrance to the said passages in each wheel being substantiallyaxial, and the discharge from the said passages being substantiallyradial, there being passages in the casing between the discharge fromone wheel and the entrance to thepassagesto the next succeeding wheel, aplurality of blades mounted between the disks of each wheel, andextending therefrom, means for admitting-air'into the casing and to theentrance to the said pas sages in the said wheels during a portion ofeach revolution thereof, to then utilize the said blades as compressor,blades, partition wallsin the casing for closing the entrance to thepassages in the wheels during the re-' mainder of each revolutionthereof, and a serlesof director Dlatesfor directing combustion gases tothe blades of each wheel during the said remainder of each revolutionthereof, for then utilizing the said blades as turbine blades, therebeing a passage in the "casingbetween eachof the said wheels for thesaid combustion gases, and inlet and out let connections for the saidcombustion gases. I

' LEON. D FOURL

